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964: Narrow/Wide & C2/C4 differences, lots of Qs

 
Old 08-12-2010, 02:25 PM
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Vandit
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Default 964: Narrow/Wide & C2/C4 differences, lots of Qs

What are the unibody and suspension component differences between a narrow and a wide 964? Are they structural differences or just bolt-on part differences?

I think I've read that all 964 unibody front ends have 2 sets of mounting points, one for narrow and one for wide. Is this true? When going wide is there any reason to go with moving the mounting points instead of just changing the wheel width/offset or vice versa?

If you have a narrow car w/ a nicely built set of suspension components (e.g. springs/struts or coilovers), are those components still compatible if you go wide or is the necessary wide hardware and different mounting points require a different set of suspension components?

My understanding is they only made 964 C4s in '89. In my research online for cars for sale, it seems like '90 C2s are pretty scarce. How do the C4s differ from the C2s structurally and suspension component wise? Is it relatively easy to turn a C4 into a RWD car (remove forward drive shaft, front diff, and front drive axles)? At that point, besides maybe front carriers and a forward output on the transaxle, what differences would exist between the converted C4 and a stock C2?

Thanks for all your help. I've always been a Porsche fan and am looking at 964s and want to learn all the ins and outs.
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Old 08-12-2010, 02:50 PM
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Makmov
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I don't know about the pick up points.

I have a 91 C4 and it was my understanding is the AWD unit is different than in a 993, which you could just remove the front drives. However, on a 964 you would need a G50 2WD transmission otherwise you loose reverse, at least that is what I was told. You would need the 2WD wiring harness and ABS unit as well.

I guess it depends on what you are going to use the car for. IMHO, it's not worth the trouble to convert a C4 to a C2 for the modest performace gains you get.
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Old 08-12-2010, 03:19 PM
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Old 08-12-2010, 03:19 PM
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jim dorociak
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I would suggest you spend the money and get the definitive book on 964 cars written by Adrian Streather. Porsche 911 Enthusiast's Companion Carrera 2, Carrera 4 and Turbo 1989-1994. It was published by Bently Publishing. All the differences between the years and so much useful information is here it is invaluable. 636 pages or so of valuable knowledge at your finger tips. [email protected]
Jim
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Old 08-12-2010, 10:53 PM
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The 964 chassis has two different mounting points on the chassis. One set for narrow body and one set for wide body. The 89 c4 might be different, I'm not quite sure on that particular year. To switch to wide body position, you need to move the suspension to the wide body, bolt the struts differently, change the tie rods, and use a wide body sway bar. This is for the front. The rears simply used a wider control arm.

If you are going to run wide body, it is better to move the suspension which changes the scrub radius than to simply bolt wider wheels with different offsets. I've done this coversion a few times.
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Old 08-13-2010, 07:08 AM
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Originally Posted by Makmov View Post
I have a 91 C4 and it was my understanding is the AWD unit is different than in a 993, which you could just remove the front drives. However, on a 964 you would need a G50 2WD transmission otherwise you loose reverse, at least that is what I was told. You would need the 2WD wiring harness and ABS unit as well.
All 2WD transmissions in all 911s after the 3.2 Carrera (which had the "short bell housing" G50) are called G50s, it is the suffix that determines the type. The AWD transmissions are called G64s.

This is a good source for both actual transmissions and information on the various types of G50s: http://www.gboxweb.com/g50specs.html

You need to replace a G64 with a G50 because the AWD system is designed to be permanently engaged, not because you lose the reverse ratio.

This is a good source for better understanding the PDAS (a.k.a., "Sputnik") AWD system found in the 964: http://www.porsche964.co.uk/technica...overviewR1.pdf

You do not necessarily need to convert any part of the braking system when performing the 4WD -> 2WD converison because the systems are fundamentally different. Once you have acquired a G50 gearbox, you can simply block off the ports for the lines going from the hydraulic solenoid valve body that usually runs to the front differential. The only downside to this method is that the "!" and PDAS warning lights will be permanently lit.

Originally Posted by Makmov View Post
I guess it depends on what you are going to use the car for. IMHO, it's not worth the trouble to convert a C4 to a C2 for the modest performace gains you get.
Agreed, it definitely depends what the driver is using the car for.

Like-for-like, tracking a 964 C4 will typically yield massive understeer, whereas a 964 C2 will be able to be tweaked into an oversteer situation (impossible in a C4). If you are tracking competitively, the "modest performance gains" can be measured in increments of full seconds.

That said, the average driver driving a 964 spiritedly or at high speeds on highways will find comfort in the inherent understeer of the 964 C4's setup, and the potential oversteer resulting from inclement conditions or from lifting off the throttle at high speeds in a C2 would soundly equate to a performance loss...
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Old 08-13-2010, 07:11 AM
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Vandit - Some of your questions are covered by the kind folks above, my $0.02:

- Due to the front differential packaging, the front portion of the 964 C4 body shell is different and has more structural rigidity than than the C2 shell.

- The MY1989 964 shell has different rear suspension mounting points than later MY 964s (since they didn't produce any Turbos/widebody shells until ~MY1991, I'm only talking about narrowbodies). In layman's terms, the mounting point is a few inches deeper in the MY1989 964s, so you will need an adaptor to fit aftermarket suspension.

The front suspension mounting points are the same for these cars as they are in the later 964s.

- They first introduced the 964 C4 in MY1989, production continued through to the early '90s.

Good luck with your search, these are great cars.
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Old 08-16-2010, 02:54 PM
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Originally Posted by Geoffrey View Post
The 964 chassis has two different mounting points on the chassis. One set for narrow body and one set for wide body. The 89 c4 might be different, I'm not quite sure on that particular year. To switch to wide body position, you need to move the suspension to the wide body, bolt the struts differently, change the tie rods, and use a wide body sway bar.
How much width does the front pick up from moving to the wide settings?
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Old 05-10-2017, 10:36 AM
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About 30mm per side / total 60mm.
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Old 05-10-2017, 10:37 AM
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Just noticed how old this was - was looking for info and ran across
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Old 05-10-2017, 10:50 AM
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From the other thread:

Originally Posted by Bill Verburg View Post
the alternate holes in the chassis are 30mm outboard on each side and given that the difference between 964 and 993 longitudinals is 5mm/side
964 longitudinals in inner holes - 0mm (stock track width)
993 longitudinals in inner holes - +5mm mm (on each side)
964 longitudinals in outer holes - +30mm (on each side)
993 longitudinals in outer holes - +35 mm (on each side)

as I noted earlier in this thread some 993Cups used the 964 long. in the outer mounts on a n/b w/ the same wheels as w/ 993 long. in the inner mounts

the cars that used the outer mounts were the 964 3.8RS, 993RSR and 993GT2 evo
all of these used 9 to 11" front wheels
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Old 09-27-2018, 10:46 AM
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Originally Posted by Geoffrey View Post
The 964 chassis has two different mounting points on the chassis. One set for narrow body and one set for wide body. The 89 c4 might be different, I'm not quite sure on that particular year. To switch to wide body position, you need to move the suspension to the wide body, bolt the struts differently, change the tie rods, and use a wide body sway bar. This is for the front. The rears simply used a wider control arm.

If you are going to run wide body, it is better to move the suspension which changes the scrub radius than to simply bolt wider wheels with different offsets. I've done this coversion a few times.
Doesnít the RSR use the narrow rear end.
obvouisly finding and purchasing the (17x11 or 12
i canít remember ) would be extremely different and costly. But Iíve heard many people say narrow body suspensions are better and or are more responsive?
If this is true why change it?
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Old 09-27-2018, 10:58 AM
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If the end goal is a widebody C2 with the turbo S rear inlets and more power what to do?
best option for the money.
A the Turbo seams like a simple solution but I am not a super fan of the top end power.
Cutting up a Turbo or widebody seams harsh.
I like the narrow rear end with 11ís like the RSR but usually not that simple.
I have found a company that makes Carbonfiber rear Turbo S Quarters.
also could you add a ball barring Turbo perhaps smaller the Turbo engine sorta retuned more like a 325 hp to feel a bit more N/A low end and throttle response.
The inlets make a huge difference in the final equation.
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Old 09-28-2018, 10:30 AM
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This is an old thread and Geoffrey no longer visits Rennlist after he sold his RSR build.

The 3.8RS/RSR does use the widebody settings from the turbo with narrow body trailing arms. the trailing arms had stiffer rubber and are not available any more.

The RS/RSR did not get the turbo arch ducts.

I wouldn't cut up a turbo and then convert it. Also so long as you use a low compression turbo engine with a single turbo you would need to convert to EFI if you want better low end power.

I am taking a different approach. I converted a NB C4 to a WB C2 RSR tribute. It uses a 993 Vram engine with low boost twin turbo twin plug etc. Also switched to a 993 6 speed with short gears and steel syncros. Before I had a defective valve failure the car was putting down 336RWHP and 335 RWTQ. It was stupidly fast at 2700 pounds. I am currently rebuilding the engine using all upgraded parts including pauter rods, ARP hardware and racing valve springs with haltech ecu. Power will have several modes but with the Haltech elite prior to engine issues we were seeing 450 tq to the wheels. I am dropping the compression ratio so something in between turbo and N/A with a low boost spring and boost controller. The curve will be quite linear and have power everywhere.

I run 993 front longitudinals on the outboard setting and 993 aluminum uprights which pushes the front end out an additional 35mm per side over a NB car. I have a set of factory RSR speedlines which fit perfectly 9 1/2" fronts ET57 and 11 ET 5 rears. I am having a set of E88's made up to make the back end 12's. Currently I am running Fikse's on track with 9" fronts and 11 rears with spacers.

I did most of the work myself with the help of some friends and wholesale pricing. Expect to drop $100k to do it minimum and correctly. I was lucky to start my project years ago with a 90 C4 donor complete for $10k.

It is also easier to use factory parts on a 91 and newer 964 tub than the earlier due to changes made over the years.
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Old 09-28-2018, 04:45 PM
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Originally Posted by cobalt View Post
This is an old thread and Geoffrey no longer visits Rennlist after he sold his RSR build.

The 3.8RS/RSR does use the widebody settings from the turbo with narrow body trailing arms. the trailing arms had stiffer rubber and are not available any more.

The RS/RSR did not get the turbo arch ducts.

I wouldn't cut up a turbo and then convert it. Also so long as you use a low compression turbo engine with a single turbo you would need to convert to EFI if you want better low end power.

I am taking a different approach. I converted a NB C4 to a WB C2 RSR tribute. It uses a 993 Vram engine with low boost twin turbo twin plug etc. Also switched to a 993 6 speed with short gears and steel syncros. Before I had a defective valve failure the car was putting down 336RWHP and 335 RWTQ. It was stupidly fast at 2700 pounds. I am currently rebuilding the engine using all upgraded parts including pauter rods, ARP hardware and racing valve springs with haltech ecu. Power will have several modes but with the Haltech elite prior to engine issues we were seeing 450 tq to the wheels. I am dropping the compression ratio so something in between turbo and N/A with a low boost spring and boost controller. The curve will be quite linear and have power everywhere.

I run 993 front longitudinals on the outboard setting and 993 aluminum uprights which pushes the front end out an additional 35mm per side over a NB car. I have a set of factory RSR speedlines which fit perfectly 9 1/2" fronts ET57 and 11 ET 5 rears. I am having a set of E88's made up to make the back end 12's. Currently I am running Fikse's on track with 9" fronts and 11 rears with spacers.

I did most of the work myself with the help of some friends and wholesale pricing. Expect to drop $100k to do it minimum and correctly. I was lucky to start my project years ago with a 90 C4 donor complete for $10k.

It is also easier to use factory parts on a 91 and newer 964 tub than the earlier due to changes made over the years.
Cobalt you are the Man on this stuff.Your car looks incredible! Iím looking for something similar with the X88 inlets and turbo S tail
A couple clarifications.
1. Rsr/rs3.8 are flaired is it just a different flair?
I think a Turbo that might have been a tracked or already altered world be the most cost effective, unless you have a different thought?
In a perfect world the 3.8 NA Engine and lowered RS.


Didnít mean to hit send but anyway it doesnít need narrow rear end persay but 12 would be Legit!

Last edited by There's no Sub!; 09-28-2018 at 05:12 PM.
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